This section is from the "Modern Machine Shop Construction, Equipment, And Management" book, by Oscar E. Perrigo. Also see Amazon: Modern Machine Shop Construction, Equipment, And Management.
Sections may be distinguished on tracings by going over the back of the tracing with a soft lead pencil, depositing enough of the lead to show well in the blueprint. If it is desired to distinguish the material of which the part is made we must resort to section lining conventionally adapted to this purpose. The mose useful of these forms are shown in Fig. 179. It will be noticed that the method is to represent similar materials by similar forms of lining, which assists in memorizing the forms; also, that the more common materials are the more simple and easy to represent. Some draftsmen prefer this plan and in addition using the soft pencil on the back for increasing the effect. It adds but little to the time of making the tracing.
Fig. 179. The Conventional Indication of Materials on Drawings.
Another much discussed question of drafting room practice is that of titles on drawings, and what may or may not be considered proper as to the matter to be included. On this subject opinions vary all the way from the use of a simple serial number to matter enough to constitute a veritable history in brief. There are several points to be considered in the matter. The title should contain enough information to be of practical use and at the same time to tell its story briefly. It should tell us what set of drawings it belongs to, naming the machine; what part of the machine it represents; the scale to which it is drawn, and the date when it was completed.
On construction drawings the date when it was commenced should also be given. It should show what draftsman drew it; when and by whom it was traced, checked, and altered. It should give the name of the establishment. Then we shall not have to refer to an index book, or to a card index whenever we wish to ascertain any of these facts; and as the foremen or workmen are not provided with these useful accessories they will not have to annoy others, or to go to the drafting room to ask questions about it, as would frequently be the case if blueprints contained, as titles, only such marks as "24-A-5," meaning that it belonged to machine No. 24, could be found in drawer A, and that it was sheet No. 5, all of which is of very little use to the man in the shop who uses it, however sufficient it may be in the drafting room.
Yet it is of use to have each machine distinguished by a symbol, or letter, and the particular tracing and blueprint by a number. These numbers begin with 1 for each machine, hence they do not usually run into more than two figures. They are a convenience to the draftsmen in finding them in the drawers, as well as of designating them briefly. This form of title is shown in Fig. 180. The plainest lettering should always be used, hence the gothic form for important letters and figures, and the draftsman's italic for the smaller ones, will be the most economical to make, the easiest to read, and consequently the best adapted to practical use both in the shop and in the drafting room.
Many methods have been advocated and experimented upon to determine the best way to mount blueprints for use in the shop. One method is to have boards half an inch thick with cleats nailed to the ends, and not increasing the thickness of the boards. These boards are painted on both sides and have the blueprints laid upon them and held down by pine strips 3/16 × ¾ inch, fastened with 8-ounce carpet tacks, for easy removal. This method renders the blueprints very convenient for the shop and preserves them well, as the strips prevent their defacement by other boards coming in contact with them. However, blueprints mounted in this manner occupy considerable space.
Another method is to mount the blueprint on heavy strawboard or binders' board. In this form an extra sheet of equally strong paper should be pasted on the back of the strawboard to prevent warping. Blueprints mounted in this manner are quite convenient to handle in issuing, returning, and storing, and with even heavy strawboard they are light and convenient for the shop. The corners should be clipped off or rounded.
Fig. 180. Title on Drawings. Usual size, 2⅛ × 3 in.
Still another method is to mount the blueprint on sheet iron. This has been tried with blueprints of moderate size, but it would seem that these can not be very convenient to handle on account of their weight, and would be liable to injure each other if piled up, by defacing the lines and figures. The edges of the sheet iron will be rather harsh to the hands. If properly performed the method of mounting blueprints upon heavy strawboard will be found as good as any for sizes of 18 × 24 inches and 24 x 36 inches, while for small work the 9 x 12 inch cards as described above will be found very useful.
Several systems are in vogue for indicating the different machines built, and these symbols are carried into the system of the drafting room for the purpose of identifying drawings. One of these methods is by distinguishing figures, another by letters, and more frequently by letters and figures combined, the one representing a class and the other indicating its place in that particular class. It will need no argument to prove that the more simple this symbol can be the easier it will be remembered, the less time it will take to represent it on drawings, and the less space and expense will be required to attach it to patterns.